I own a 98 Dakota Sport with a 3.9L V6 Magnum. I have a huge ongoing problem. I keep blowing the upstream (before cat) O2 sensor, also I'm emmiting a black powdery residue which is believed to be carbon. I've been to 4 general mechanics, 3 dodge dealerships, and 2 Dodge specialty mechanics. None can come up with any ideas. The only thought was that the engine was burning and recycling oil and the buildup in the exhaust would blow the sensor, but no-one can find a leak in the entire GD engine!!!!! I'm desperate!!! I'm driving it from Massachusetts to Florida and need to know that it's running properly. Any thoughts would be unbelievably appreciated. Thanks in advance.

 

im sure you have, but has the engine been scanned?

 

Yes it has. I got the code p0171 which told me the engine was running rich (i already knew that) one of the mechanics suggested replacing the o2 sensor and when i did the light went off. but then it blew that o2 also.

 

does it get especially poor fuel mileage?

 

I get about 5-7 mpg.

 

sounds to me like you have some burnt valves, possibly a bad cam, or a TB issue.

 

I'll have those looked at, Thanks. Any other ideas?

 

well, if its running THAT rich..and has that poor of mileage something has to be haning open...like something in the TB or a cam timing issue..

 

Does it seem possible that its the Intake Manifold Gasket because thats been mentioned as a possibility??

 

It turned out to be the Intake manifold Plennum gasket. the suction had actually ripped part of the gasket out. Thanks to BadStratRT for all the help.